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DirectX:Direct3D:Tutorials:VB:DX8:DirectShow
DirectShow is used to play videos. It can also play MP3's. Initialization Start a new project, then add a Module. The first thing that needs to be done is to add a Reference to the Active Movie Control Type Library in the Project->References... menu item. All code will be placed in the module. Private dx_BasicAudio As IBasicAudio Private dx_BasicVideo As IBasicVideo Private dx_MediaEvent As IMediaEvent Private dx_VideoWindow As IVideoWindow Private dx_MediaControl As IMediaControl Private dx_MediaPosition As IMediaPosition Each object is used to control the seperate processes of DirectShow (Audio, video, events, the output window, controls and position). Clean up Public Sub CleanUp() On Error GoTo CleanUpError: 'If the MediaControl has been initialized, then stop it. If ObjPtr(dx_MediaControl) > 0 Then dx_MediaControl.Stop End If 'Destroy all objects If ObjPtr(dx_BasicAudio) > 0 Then Set dx_BasicAudio = Nothing If ObjPtr(dx_BasicVideo) > 0 Then Set dx_BasicVideo = Nothing If ObjPtr(dx_MediaControl) > 0 Then Set dx_MediaControl = Nothing If ObjPtr(dx_VideoWindow) > 0 Then Set dx_VideoWindow = Nothing If ObjPtr(dx_MediaPosition) > 0 Then Set dx_MediaPosition = Nothing CleanUpError: End Sub This sub will stop any media that is currently playing, and release all the memory from objects that may have been loaded. Its important to run this sub before loading a new media file, and also when you exit the application. Loading Media Public Sub LoadMedia(ByVal DstHwnd As Long, Filename As String) On Error GoTo LoadMediaError 'clean up any media that may be loaded already CleanUp 'attach the filter graph manager to the media control Set dx_MediaControl = New FilgraphManager 'process the media Call dx_MediaControl.RenderFile(Filename) 'attach the media control to the audio object Set dx_BasicAudio = dx_MediaControl 'reset the volume and balance dx_BasicAudio.Volume = 0 'Loudest dx_BasicAudio.Balance = 0 'Centered 'attach the media control to the video window Set dx_VideoWindow = dx_MediaControl 'set the window style to none. dx_VideoWindow.WindowStyle = 0 'ensure the video window is in the right place dx_VideoWindow.Top = 0 dx_VideoWindow.Left = 0 'play the video only on the destination dx_VideoWindow.Owner = DstHwnd 'attach the media control to the events Set dx_MediaEvent = dx_MediaControl 'attach the media control to the position Set dx_MediaPosition = dx_MediaControl dx_MediaPosition.Rate = 1 'Normal forward playback speed LoadMediaError: End Sub This sub will initialize all the DirectShow objects, and load your media file. Notice that you have to attach something called a filgraphmanager to your media control object. According to Microsoft, the filgraphmanager manages the run, pause, and stop functions. In order to play MP3 files, you need to skip all the dx_VideoWindow calls in the LoadMedia sub. If you don't, it will cause an error and will not play. Play, Pause and Stop Play Public Sub PlayMedia() On Error GoTo PlayMediaError: If dx_MediaPosition.CurrentPosition = dx_MediaPosition.Duration Then dx_MediaPosition.CurrentPosition = 0 End If Call dx_MediaControl.Run PlayMediaError: End Sub Pretty easy, if the current position is the same as the duration, then reset the position to zero, then play the media. Pause Public Sub PauseMedia() On Error GoTo PauseMediaError: Call dx_MediaControl.Pause PauseMediaError: End Sub In order to un-pause, you must call dx_MediaControl.Run again. Stop Public Sub StopMedia() On Error GoTo StopMediaError: Call dx_MediaControl.Stop dx_MediaPosition.CurrentPosition = 0 StopMediaError: End Sub Stop the media, and reset the position to zero. Final thoughts Well thats all there is to it. As you can see, there are many things you can do to the playback of videos. Notice in the LoadMedia sub, that dx_VideoWindow has a .Left and .Top property. There is also a .Width and .Height property as well, which can be used to adjust the playback size of the video. Also you can adjust the speed of the video using dx_MediaPosition.Rate. Since 1 is normal speed, .5 is half speed and 2 is double speed. Moglor 10:01, 1 September 2006 (EDT)